CALIFORNIA, Sept 19 — New US research has found that small particles of soot and dust from air pollution can affect the thyroid development in foetuses, possibly putting children at risk from health problems later in life.
Carried out by researchers from the University of Southern California (USC) and published in the journal JAMA, the new study looked at 2,050 newborn babies who had blood tests taken straight after they were born in order to measure levels of thyroxine (TT4), a hormone secreted by the thyroid gland.
During pregnancy, the babies’ mothers had also reported on exposure to air pollution including ozone, nitrogen dioxide, PM10 particles, which are particles of pollution less than 10 microns or 10 millionths of a meter across, and the smaller PM2.5 particles.
The researchers found that when the mothers’ exposure to PM2.5 increased by 16mg per cubic metre of air — around the volume of a dishwasher — TT4 levels in blood increased 7.5 per cent above average levels in babies.
When the mothers’ exposure to PM10 increased by 22mg per cubic metre, TT4 levels increased by 9.3 per cent.
However, no increases in TT4 were found with exposure to other air pollutants, such as ozone or nitrogen dioxide.
The team also found that exposure to PM10 during one to eight months of pregnancy was associated with significantly higher newborn TT4 concentrations, while exposure to PM2.5 was most significant during months three to seven of pregnancy.
The research is the first to track effects of pollution month by month on changes in thyroid hormones, which are critical for foetal growth, metabolism, and neurodevelopment.
“Air pollution is bad for adults and children, and this study shows it may be bad for the foetus too, despite being protected in the womb,” said Carrie V. Breton, corresponding author of the study. “Thyroid function is important for lots of elements of life and tweaking that in utero may have lifelong consequences.”
“There are several places around the world where air pollution is skyrocketing,” continued Breton. “This is another example of an environmental exposure that affects early development in subtle ways, and we don’t know the health consequences.”
New research presented on Sunday at the European Respiratory Society International Congress also showed for the first time ever that tiny particles of carbon, which are usually created by burning fossil fuels, can be passed to the placenta. Researchers from Queen Mary University of London, UK, looked at five pregnant women living in London and found that when the women inhaled polluted air, the sooty particles are able to move from the lungs to the placenta via the bloodstream.
Previous research has also linked pregnant mothers’ exposure to air pollution to premature birth, low birth weight, infant mortality and childhood respiratory problems. — AFP-Relaxnews
